We are currently witnessing a major shift in the field of lighting, due to constantly improving performance in electroluminescent diodes better known by the abbreviation LED. For several years now, electroluminescent diodes have been proposed which individually have limited light-emitting efficiency such that several need to be grouped side by side to give out adequate lighting power, clearly inferior to that of superior filament lamps.
More recently, electroluminescent diodes with high light-emitting efficiency capable of rivalling filament lamps have appeared, with a view to progressively replacing them in the near future.
But an electroluminescent diode of this type preferably needs to be cooled to stabilise its operating temperature at a given value, for example of the order of 60 to 70° C.
In the field of semi-conductors, for example, it has been known for many years to cool power components by mounting them on radiators with strong thermal coupling to dissipate any heat released, by conduction then natural air convection. Radiators proposed for this purpose are either moulded in an aluminium alloy, or extruded in a comparable alloy, the extruded profile then being cut to the preferred length corresponding to the thermal power to be dissipated. Moulded or extruded radiators are very expensive components. In the case of moulding, moulds have to be provided for all required dimensions and it is not easy to reconcile production rates with the needs of the lighting market, such as it is occurring with the appearance of these novel LEDs. Extrusion is also a costly process and is complicated to implement. In both cases, cooling fins which are defined in such radiators all around the location of the component to be cooled are relatively thick, due to the moulding or extrusion techniques themselves, for any given thermal exchange surface. This results in a heavier radiator than would be possible to produce, due to cooling by equal convection, with a radiator having thinner fins. The mass of metal required, generally fairly costly aluminium ensures that this cooling radiator cannot be optimised and that its retail cost remains necessarily high.